In so-called progressive die systems, workpieces formed from strip stock remain attached to webs that extend along lateral edges of the pieces to facilitate indexing of the workpieces through the sequential stations of the die assembly. While such arrangements facilitate conveyance of the workpieces through the die stations, they possess the disadvantage that the workpieces must be formed in a linear array at space locations along the strip stock, leading to substantial material inefficiency and waste. Furthermore, the fact that all workpieces remain interconnected during at least a major portion of the die operation can lead to difficulty and inefficiency in performing operations on the workpieces at a given station. For these reasons and others, so-called transfer die systems have been developed in which the workpieces are pre-separated and fed as individual units to the die arrangement. A transfer die system of this character permits more efficient use of the strip stock material, and also permits greater flexibility in operations that can be performed at the individual die stations. However, the conveyor arrangement for indexing individual workpieces through a transfer die system is more complex than those in typical progressive die systems, usually involving release and re-engagement with the workpieces at each of the individual die stations.
A general object of the present invention, therefore, is to provide a transfer die system of the described character that features an improved conveyor for indexing workpieces sequentially through the individual die stations. Another and more specific object of the present invention is to provide a transfer die system in which the workpiece conveyor is of simplified construction that moves unidirectionaly through the die system, in which workpieces are automatically loaded onto and/or unloaded from the conveyor by movement of the die press, in which the conveyor retains engagement with the workpieces while operations are performed on the workpieces at the die working stations, and/or that may be readily modified for use in conjunction with sheet workpieces of differing geometries and configurations.